This invention relates to the generation and use of ultrahigh-pressure fluid under controlled temperature conditions, and more particularly, to a system for changing the temperature of a pressurized fluid.
Ultrahigh-pressure fluid has numerous uses. For example, ultrahigh-pressure fluid, generated by an ultrahigh-pressure pump, may be directed through a nozzle to form an ultrahigh-pressure fluid jet, which may or may not be mixed with abrasive material. Depending on the characteristics of the ultrahigh-pressure fluid jet, the jet may be used to cut or clean a variety of surfaces and objects, as is understood in the art. Ultrahigh-pressure fluid may also be directed to a pressure vessel to pressure-treat a substance. For example, it is known in the art that pathogens and microorganisms in substances, for example food, may be inactivated by exposing the substances to high pressure. While generating an ultrahigh-pressure fluid jet with fluid at ambient temperature provides acceptable results in many applications, applicants believe that it may be desirable in some situations to provide pressurized fluid for use at a selected temperature, above or below ambient. The present invention is therefore directed to selectively heating or cooling ultrahigh-pressure fluid.
Briefly, the present invention provides ultrahigh-pressure fluid at a selected temperature for use in any application that calls for the use of ultrahigh-pressure fluid. In preferred embodiments, the fluid is heated or cooled after it is pressurized. This is in contrast to heating or cooling the fluid prior to pressurization, which applicants believe may negatively affect the performance of an ultrahigh-pressure pump, particularly at extreme temperatures.
In a first preferred embodiment, ultrahigh-pressure fluid flows from its source, for example an ultrahigh-pressure pump, to its point of use, through ultrahigh-pressure tubing. The ultrahigh-pressure tubing is passed through a plurality of thermally conductive blocks, each block having a first bore through which the tubing passes. Each thermally conductive block is provided with a second bore, into which is positioned a source of heating or cooling. For example, a cartridge heater may be inserted into the second bore and set to a selected temperature. Alternatively, fluid at a selected temperature may be circulated through the second bore. In this manner, each thermally conductive block works as a heat exchanger, to create a heat flux across the ultrahigh-pressure tubing, thereby increasing or decreasing the temperature of the ultrahigh-pressure fluid, as desired. In a preferred embodiment, a thermocouple is provided in each block to sense the temperature of the block and/or the outer surface of the ultrahigh-pressure tubing, and provide feedback to a control loop, that in turn adjusts the temperature of the source of heating or cooling.
In another preferred embodiment, electrical resistance is used to heat the ultrahigh-pressure fluid as it flows through ultrahigh-pressure tubing. More particularly, a plurality of electrodes are coupled to an outer surface of the ultrahigh-pressure tubing and to a source of current. Preferably, a high current with a low voltage is used to reduce the likelihood of electric shocks. By passing a large current through the tubing, the entire cross section of the tubing effectively becomes the heat source. Without limiting the invention in any way, this invention may be particularly well suited to applications where heating to a high temperature is desired.
It will be understood that the number of blocks used and the arrangement of the blocks will be selected based on design parameters and the task at hand. For example, in a preferred embodiment, the number of blocks and the temperature of each block is selected based on the desired temperature of the ultrahigh-pressure fluid at the point of use, and the flow rate through the tubing.